There's another chip on the table in the NFL's conflict with its players over a collective bargaining agreement. The league wants testing for human growth hormone included in the deal, FoxSports.com reported Thursday.

The substance is now banned by the NFL, but it doesn't test for it. Why? The players' union pushed for that contrary position under former leader Gene Upshaw.

The league sees HGH testing as a "necessary" part of a new collective bargaining agreement, NFL vice president and general counsel Adolpho Birch told FoxSports. Birch runs the league's drug testing program.

"We want it. We think it's necessary. We're going to ensure that it's done," Birch said. "That's something very important to us and the integrity of our game. We believe some of the basis for going slowly on it before has been addressed. At this point, it's proper for it to be an active part of our program."

Adding HGH testing was broached in negotiations before the league and the union broke off talks on March 11. It has been an issue for the past couple years, with the NFL first proposing HGH testing in January 2010.

Human growth hormone can only be detected by blood tests. Other drug tests administered by the NFL involve urine samples.

As for blood samples, Upshaw had a reason for his stand.

"We've got a lot of big, tough guys, but even they don't like to be pricked on the finger to give blood," Upshaw said.

With no collective bargaining agreement, neither a prick nor a urine test is possible because the NFL can't demand player testing. So players who are working out on their own or rehabbing from injuries are free to use any means until a contract is reached.

Wondering why HGH testing is a concern? In its report, FoxSports noted a 2009 comment from Tampa Bay Buccaneers running back Earnest Graham that its use was widespread.

"I'd say a lot of NFL players are doing it," Graham told Tampa radio station WQYK-AM. "Any sport [where] guys come across injuries and need to get back fast and come back stronger than they were before, I wouldn't be shocked."

Minor league baseball and International Olympic Committee test for HGH. Major North American professional sports do not.

Synthetic HGH has been approved to treat adults who have true growth hormone deficiency, according to the Mayo Clinic. However, Mayo's website also notes: